May 24, 2012 8:35 PM

Wonder if anyone can help identify this flying bug. It's in our Kitchen and Dining Room. They seem to be breeding as we're getting 100+ per day in the hot weather and around 50+ per day when it's cooler. They're attracted to the light and generally congregate on the ceiling. Approx 3-4mm long.

I'm working my way around the rooms trying to find where they're coming from but all I've found so far are what appear to be discarded wings/shells but nothing else. Still plenty of places to look but having an idea of what it is, it's habits and what it's living off would really help.

I took a look at the one you mentioned. Although, in the pictures I looked at, it didn't seem an exact match I did notice that it mentioned the larvae live in water. The interesting thing here is that I found a slight water leak under the kitchen cupboards so water was pooling on the concrete floor. I would have expected just a wet floor there but it seemed to have round black patches in it for no good reason. We've repaired the leak and dried the entire area with blowers and gradually over a week the numbers have reduced to the point where we're only getting 3-5 a day now.

I have also now seen these insects outside the back door that leads into the kitchen so my suspicion is that they just came in through a gap, discovered the water and set up home.

Lewis,

I hadn't mentioned it in my original post but we'd gone through all the food cupboards and there was no sign of any activity. The bird food (peanuts in this case) is stored elsewhere in the house where we've not had a problem with the insects so it doesn't appear to be that.

Wayne,

It's been a strange one because overnight these little devils hide away in all manner of places, corners, behind skirting boards, gaps in the windows and other places, but none of those showed any signs of being the place where they were reproducing. I systematically sealed off every gap, joint and appliance throughout the two rooms to try and pinpoint the problem which led me to finding the water leak mentioned above.

Hopefully we've dealt with the problem now but if anyone has any other comments on what it is I'd still very much appreciate it.

Thanks Episcophagus. I took a look at that site and a quick google image search and it looks a very close match. I struggled to find any info describing its habits though. Any suggestions where I might read up on it?

I agree with Episcophagus: these are beetles known as Marsh BeetlesCyphon sp. (family Scirtidae, formerly known as Helodidae). There are 10 very similar species in Britain and I can’t identify these to the level of species, because there is no identification key published in Britain. They are found near water, where their larvae – which resemble woodlice – develop.

The larvae are filter-feeders in aquatic habitats, mainly in stagnant water. The adults are terrestrial and may be found flying among vegetation, usually near the larval habitat. These beetles are poorly known, and usually we get only males in collections.

I don’t know why they come into your house. It may be close to some stagnant water, which may be just a water butt where you collect rainwater. The larvae pupate near their breeding site, so that may explain why they emerge in your house, then try to escape towards the light at the windows. I don’t think they can be pests to food, carpets or wood, and they may be just a nuisance. Making sure they do not breed in a water container or pond near the house may solve the problem.

Please follow the link below to see photos of all species found in Britain, plus a European one:

Thanks Florin. I'm fairly sure they were breeding in the house due to a water leak behind the sink leaving a pool of water. Now that we've fixed that we're only getting a handful in the house each day, so not much of a nuisance now. I suspect this may be through ill fitting doors/windows as we live in an old cottage. I'll see if I can find another breeding site outside.